1. Field of the Invention
This invention relates to a preparation for treating immune complex diseases, more particularly to a preparation containing N-acetylneuraminic acid as an effective substance.
2. Related Art Statement
The term "antiallergic agent" has been used to describe a compound which inhibits disengagement or production of chemical mediators against allergic reactions, particularly the type I allergic reaction.
As the reasons, there have been considered that (1) among the allergic reaction, those which can be seen in many cases are the type I allergic reaction, (2) histamine disengagement which is one of the main mediators of the type I can be caused also in the type II or III, and histamine is one of the most important factors which modify the type IV reaction, and (3) for therapy of diseases due to the other type II, III or IV allergic reaction, steroids have often been used.
Among the allergic reactions other than the type I, the type III allergic reaction is classified into an immediate allergy as in the type I allergic reaction, and is an allergic inflammation reaction which is participated in an antigen-antibody complex (immune complex), a complement and a polymorphonuclear leukocyte (mainly neutrophils).
As a representative disease, there may be mentioned systemic lupus erythematosus (SLE), complex glomerular nephritis, serum disease, etc., but since the type III allergic reaction is called Arthus reaction as a byname, the representative experimental model is referred to as the Arthus reaction.
The Arthus reaction is an inflammation reaction which can be observed particularly on the skin as edema and bleeding, and its main reaction sequence includes (1) sedimentation of immune complex at vessel wall and surrounding tissues, (2) activation of complement system through classical pathway (partially, through the alternative pathway), (3) aggregation of polymorphonuclear leukocytes to a reaction site, (4) immune adhesion of polymorphonuclear leukocytes to materials and cells in which C3b is coated thereon, (5) reinforcement of phagocytosis of polymorphonuclear leukocytes, (6) release of lysosomal enzyme from polymorphonuclear leukocytes, and (7) disorder of cells (erythrocytes, etc.) and tissues.
In vivo, a material which combines with heteropolysaccharides in various ways and carries biological functions as an important constituent for the heteropolysaccharides, is sialic acid.
With regard to the biological functions of sialic acid in an immune system, research has reported that it shows specific antigenic properties, is an essential component for the receptor molecule, and exhibits anti-recognition effects that mask the immune recognition site.
These effects can be obtained with a bound type sialic acid. As the reason, there may be considered that (1) in conventional research on the biological function of the sialic acid, special attention has been given to how the physiological activity of the substrate is influenced by removing the sialic acid bound to heteropolysaccharides (particularly the cell membrane) with sialidase, or by effecting modification such as periodate oxidation, etc., (2) it is difficult to quantitatively analyze sialic acid since the amount of free type sialic acid present in blood is minute.
In recent years, it has been reported that N-acetylneuraminic acid which is one of the most representative sialic acids shows antiviral effect or anti-inflammatory effect [(1) Lobert L. Hess, et al., The Journal of Immunology, vol. 127, No. 5 (1981), pp. 1740-1743; (2) P. Gorog, et al., Agents and Actions, vol 8, No. 5 (1978), pp. 543-545; (3) Hiromi Ito, et al., Pharmacology and Therapy, vol. 13, No. 7 (1985), pp. 479-494, et al].
However, little is know about the physiological properties, particularly the pathophysiological properties of N-acetylneuraminic acid, and pharmacological investigation has been inadequate.